Disclaimer: The categories and qualifications below are subjective. E.g. what is and isn't manga is a matter of nuance, and I'm no expert. But if it's listed, it means I like it.
Category-defying
- Lackadaisy Cats
- Exquisitely researched and drawn Prohibition-era story with anthropomorphic cats. Very cute and humorous, with occasional non-graphic violence.
- Girl Genius
- Hugo Awards-winning gaslamp fantasy. Comedy and adventure galore.
- Looking For Group
- Ha-ha-only-serious fantasy; loosely based on a certain major MMORPG.
- Kukuburi
- Weird, weird parallel world fantasy.
- Paradigm Shift
- Police drama with werewolves and a surprising twist.
- Order of the Stick
- Stick figure fantasy adventure/comedy; intelligent humor; some nerdy references.
- Mysteries of the Arcana
- Science-fantasy(?) adventure; some humor and mature side themes.
- Red's Planet
- Ha-ha-only-serious slice-of-life with a little foster home girl abducted by aliens.
Gag strips
- Oglaf.com
- NSFW warning! Hilarious (if sometimes gross) dismantling of fantasy cliches. Intelligent humor. NOT for children.
- Doomed to Obscurity
- Jokes about computer nerds.
- The Noob
- Goofy MMORPG parody; rarely updated nowadays.
- XKCD
- Nerdy gag-a-day; often very smart; stick figures.
Comedy
- Questionable Content
- Slice-of-life with science fiction undertones; very intelligent.
- Freefall
- Hard SF comedy.
- Darths and Droids
- The Star Wars prequel trilogy retold as a tabletop RPG campaign. Photo comic.
- Ménage a 3
- Hilarious slice-of-life with sex-obsessed nerds. Lots of gratuitous nudity. NSFW.
- I Was Kidnapped By Lesbian Pirates From Outer Space!!!
- Affectionate spoof of 1930es pulp sci-fi. Occasionally NSFW.
- Shortpacked!
- Somewhat absurdist slice-of-life set in a toy store; lots of nerdy and gay references.
- Weregeek
- Just what it says on the tin. Think about it for a moment.
- 2nd Shift
- Slice-of-life with copy shop clerks assaulted by weirdness; on hiatus waiting for a new artist.
- Sacred Grounds
- Slice-of-life with vampires and werewolves manning (heh) a cafe. Still new.
- I Dream of a Jeanie Bottle
- Slice-of-life with a newbie (and unwilling) genie.
- Spinerette
- Goofy superhero comedy with manga influences. Lots of fanservice.
- 2D Goggles
- Steampunk parody of real life. Well rooted in actual history. A bit chaotic.
Superheroes
- Union of Heroes
- European superhero comedy; photo comic. It's grown weird.
- Johnny Saturn
- Traditional superhero story. First issue was positively stunning.
- Heroes, Inc.
- Alternate history with superheroes; interesting take.
- Superseed
- Yet another superhero story with a twist. Possibly discontinued.
Vampires
- Vampirates!
- Western Manga slice-of-life urban fantasy with gay vampire pirates. Serious. Apparently discontinued.
- Anathema
- Historical vampire adventure/drama.
- Love is in the Blood
- Horny vampires playing Indiana Jones (formerly Abandon: First Vampire).
- School Bites
- Manga slice-of life comedy with vampire high-schoolers.
Space Opera
- Crimson Dark
- Space opera / cyberpunk; rotoscoped 3D graphics, good characters and drama.
- Outsider
- Well-drawn Western Manga space opera. Blue-skinned space babes FTW!
- Dreadnought Invasion Six
- Little space opera time waster. Finished.
- Spacial
- Space opera; simple graphics, nice story. Apparently discontinued.
Fantasy
- Inverloch
- Western Manga fantasy; finished.
- The Phoenix Requiem
- Western Manga victorian fantasy.
- Dominic Deegan, oracle for hire
- Realistic adventures in a magical world.
- Twokinds
- Human, furries, magic and nudity in a world of dark conspiracies. Possibly NSFW.
- Garanos
- Generic but good fantasy; nice drawing style. Finished.
- The Next Adventure
- Subtler-than-it-looks urban fantasy. On hiatus.
- Locus
- Graphic violence and nudity in a very dark version of our world. NSFW. Not for children, the squeamish or devout Christians.
- Beauty and the Beast
- A re-telling of the classic story.
- Wooden Rose
- Western Manga; historical slice-of-life/fantasy.
- Wayfarer's Moon
- High fantasy adventure.
- Strays
- Manga fantasy.
Other Science Fiction & Fantasy
- FreakAngels
- Post-apocalyptic slice-of-life with psionics.
- Moon Town
- Hard(?) science fiction comedy(?) On hiatus.
- A Miracle of Science
- Hard SF/Post-singularity; policier/romance with manga influences; finished.
- Afterlife Blues
- Cyberpunk/space opera thriller. By the authors of A Miracle of Science.
- Omega Chase
- Time travel / space opera / fantasy western. Possibly discontinued.
- Transpose Operator
- Intriguing little post-apoc piece. Updates slowly.
- Reaper 7
- Post-apocalyptic drama. Discontinued. (Dead link: http://crimsonnight.net/)
- A Distant Soil
- 1980es science fiction revived as a webcomic. Psionics and shapeshifters.
- Alpha Shade
- Biplanes, flying battleships and magical creatures.
- The Dreamer
- Time travel romance.
- Unity
- Posthuman science fiction with furries. Whimsical graphics, good drama. Finished.
- Memories of Paradise
- Soft sci-fi with a spiritual/religious theme and a classic feel. Finished.
- The Jenny Everywhere Chronicles
- Multiverse-hopping adventures with an open source character.
- 6-Commando
- Alternate reality Cold War story. Futuristic, good drama.
Others
- Marilith
- Manga hitman thriller... comedy? NSFW. Finished.
